1. Field of the Invention
The present invention relates to an improved OHV engine in which a pair of cylinder blocks provided with a plurality of cylinder bores is connected to the crankcase. Power from a cam provided on a camshaft interlocked with and connected to a crankshaft and stored in the crankcase is transmitted to rocker arms pivotably supported on cylinder heads connected. respectively. to both of the aforementioned cylinder blocks via connecting rods.
The present invention also relates to a valve gear mechanism of an engine in which a supporting shaft having both ends thereof facing towards the wall provided by the engine body is inserted into and supported by shaft supporting members provided in the aforementioned engine body at a plurality of positions spaced axially of the supporting shaft. A plurality of arms are pivotably supported by the supporting shafts. More specifically, the invention relates to an improved arm supporting structure.
2. Description of the Background Art
Hithertofore, an OHV engine is known wherein cams are provided on a camshaft in a crankcase and rocker arms on the cylinder head sides are interlocked and connected via a connecting rod as set forth in JP-U-64-36654.
In such OHV engines, it is already known to provide an engine wherein each connecting rod being stored in part in a pipe member disposed at a position away from an outer wall of the cylinder blocks so as to connect between the crankcase and the cylinder heads for allowing smooth movement of the plurality of connecting rods without interference from the outside.
However, when employing the structure in which a pipe member is disposed for each connecting rod for a V-type or a horizontal opposed engine having a pair of cylinder blocks on which a plurality of cylinder bores are disposed adjacent to each other in the direction of the axis of the crankshaft, the arrangement of a connecting boss for pipe members may be limited and thus the distance between cylinder bores cannot be reduced easily when downsizing the engine by minimizing the distance between the cylinder bores. In addition, the number of pipe members increases, and thus the number of components increase and the number of assembling steps increases as well.
In order to solve such a problem, it is conceivable to store all the connecting rods in a rod storage chamber provided in the cylinder heads, the cylinder blocks, and the crankcase between the adjacent cylinder bores on the respective cylinder blocks. However, the number of connecting rods that can be arranged between the adjacent cylinder bores is limited in the case of reducing the distance between the adjacent cylinder bores.
Hithertofore, as disclosed in JP-A-8-226310, a valve gear mechanism is known wherein a rocker shaft that corresponds to a supporting shaft is inserted into and supported by a plurality of shaft supporting members provided integrally on the cylinder head, and a rocker arm is pivotably supported by the rocker shaft.
However, in the aforementioned related art, the rocker shaft is formed integrally along the whole axial length. When the sidewall of the cylinder head faces towards the end of the rocker shaft, an opening for inserting the rocker shaft is formed on the sidewall in advance, and then a member for closing the aforementioned opening is attached after insertion of the rocker shaft during assembly of the valve gear mechanism. Therefore, an extra part is required, as well as the number of assembling steps increases. In this case, though employing a structure in which each shaft supporting member may be divided into an upper part and the lower part may solve the aforementioned problem, the costs may be increased.